On-Chip RF Shields with Through Substrate Conductors
Structures of a system on chip and methods of forming a system on chip are disclosed. In one embodiment, the system on a chip includes an RF component disposed on a first part of a substrate, a semiconductor component disposed on a second part of the substrate, the semiconductor component and the RF component sharing a common boundary. The system on chip further includes through substrate conductors disposed in the substrate, the through substrate conductors coupled to a ground potential node, the through substrate conductors disposed around the RF component forming a fence around the RF circuit.
This patent application relates to the following commonly assigned co-pending applications concurrently filed, each of which is hereby incorporated herein by reference:
This invention relates generally to electronic devices, and more particularly to RF shields with through substrate conductors.
BACKGROUNDSemiconductor devices are used in many electronic and other applications. Semiconductor devices comprise integrated circuits that are formed on semiconductor wafers by depositing many types of thin films of material over the semiconductor wafers, and patterning the thin films of material to form the integrated circuits.
There is a demand in semiconductor device technology to integrate many different functions on a single chip, e.g., manufacturing analog and digital circuitry on the same die. In such applications, many different components such as digital and analog or RF circuitry are integrated into a single chip. However such integration creates additional challenges that need to be overcome. For example, integration of multiple components results in interference between various components. RF circuits operating at high frequencies produce extraneous electromagnetic radiation that interferes with the operation of other components in the integrated system on chip. This problem is getting worse with subsequent technology generations as operating frequencies continuously increase. Aggressive integration of multiple components in a single chip requires the need to eliminate such interference without a significant increase in production costs.
SUMMARY OF THE INVENTIONThese and other problems are generally solved or circumvented, and technical advantages are generally achieved, by embodiments of the present invention.
Embodiments of the invention include structures for shielding semiconductor components on a system on chip comprising an RF component from electromagnetic radiation originating from the RF circuitry of the RF component. In accordance with an embodiment of the present invention, the system on the chip comprises an RF component disposed on a first part of a substrate, a semiconductor component disposed on a second part of the substrate, the semiconductor component and the RF component sharing a common boundary. The system on chip further comprises through substrate conductors disposed in the substrate, the through substrate conductors coupled to a ground potential node, the through substrate conductors disposed around the RF component forming a fence around the RF circuit.
The foregoing has outlined rather broadly the features of an embodiment of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of embodiments of the invention will be described hereinafter, which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.
For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTSThe making and using of the presently preferred embodiments are discussed in detail below. It should be appreciated, however, that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention.
The present invention will be described with respect to preferred embodiments in a specific context, namely a structure comprising through substrate vias forming an RF shield, and methods of forming the RF shield comprising the through substrate vias. In various embodiments, the invention avoids the use of separate shielding layers disposed outside the chip (for example, during packaging). The present invention avoids expensive fabrication costs by integrating the RF shield on-chip rather than being separately attached to the chip. Further, being an integrated RF shield, the manufacturing steps are commonly shared with other components already being used in the fabrication of the system on chip (SoC). Although illustrated with respect to shielding adjacent components on an SoC, the invention may be applied to shielding single chips from adjacent chips.
According to SoC requirements, analog, RF, digital, and memory blocks must all coexist on-chip while interacting minimally (such as generating minimal noise and being highly immune to the received noise). In particular, as operating frequencies increase with scaling, RF components operating at high GHz frequencies emit electromagnetic radiation that interferes with other neighboring components. In various embodiments of the present invention, a conductive shield surrounds the RF components to minimize this interference. The conductive shield blocks out the electromagnetic radiation generated by the RF circuitry from reaching other components of the SoC.
A structural embodiment of the invention illustrating a top view of a conductive cage will be first described using
An embodiment of the invention is illustrated in
In various embodiments, electromagnetic radiation emitted by the RF component 1 is shielded by an RF shield 8. The RF shield 8, in one embodiment, comprises vertical sections (vertical fence 20) passing through the substrate 10. In various embodiments, the RF shield 8 comprises through substrate conductors 25 electrically coupled to a node coupled to a ground potential. The through substrate conductors 25 may comprise different shapes and be arranged to minimize fabrication costs while maximizing the electromagnetic shielding.
The through substrate conductors forming the vertical fence 20 of the RF shield 8 are described in
Referring to
In one embodiment, the through substrate vias 21 are wider and about 20 to about 100 μm wide with aspect ratio's in the range of about 3:1 to about 5:1 (
Referring to
The fence 20 in one embodiment may be formed as through substrate trenches 24 (
In some embodiments, redistribution lines provide connections (not illustrated) coupling the front side circuitry to other components of the chip using the through substrate conductors 25.
Referring to
Interconnect layers 60 are disposed above the substrate 10 and comprise the metallization levels that interconnect the circuit. For clarity, the metallization levels on the interconnect layer 60 are illustrated in regions 2.
The substrate 10 in various embodiments comprises a bulk mono-crystalline silicon substrate (or a layer grown thereon or otherwise formed therein), a layer of (110) silicon on a (100) silicon wafer, or a germanium-on-insulator (GeOI) wafer. In other embodiments, other semiconductors such as silicon germanium, germanium, gallium arsenide, indium arsenide, indium phosphide, indium gallium arsenide, indium antimonide or others can be used with the wafer. The substrate 10 also includes active components such as transistors or diodes, or passive components such as capacitors, inductors or resistors, among others. Active regions are disposed on a top surface of the substrate and comprise devices such as transistors, resistors, capacitors, diodes, etc. Metallization levels are disposed over the top surface of the substrate 10.
The through substrate via 21 couples to a contact plug 59 disposed above the substrate 10. The contact plug 59 electrically connects to the through substrate via 21. Accordingly, the through substrate via 21 is formed before forming the contact plug 59. In various embodiments, hence, the through substrate via 21 is formed before, during, or after formation of the active devices.
The contact plug 59 is electrically coupled to a ground potential through the interconnect layer 60. In some embodiments, the through substrate via 21 is also electrically connected with other parts of the active circuitry through the contact plug 59. The contact plug 59 couples to the gate electrode 58 over the active devices, whereas over the through substrate via 21 the contact plug couples to the conductive filling of the through substrate via 21.
The contact plug 59 is coupled to upper metallization levels through first metal lines 63. The first metal level comprises first metal lines 63 disposed over the substrate. The first metal lines 63 are disposed over a first metallization insulation layer 61. The first metallization insulation layer 61 is disposed over the substrate and around the contact plug 59 and on top of through substrate via 21. A second metallization insulation layer 62 is disposed over the first metallization insulation layer 61. The first metal lines 63 are embedded in the second metallization insulation layer 62. The interconnect layer 60 further comprises a first via 64 disposed on the first metal lines 63, and a second metal line 65 coupled to the first via 64.
A first conductive layer 41 is disposed in the inner region of the through substrate via 21, and electrically couples the contact plug 59 to the back side of the substrate 10. The first conductive layer 41 comprises copper, although in other embodiments other conductive materials such as doped polysilicon, tungsten, aluminum, silver, gold, nickel, palladium, or a combination thereof are used.
A sidewall dielectric layer 26 is disposed around the through substrate via 21 and electrically isolates the first conductive layer 41. The sidewall dielectric layer 26 is an oxide such as silicon oxide, or a nitride such as silicon nitride, silicon oxynitride, or organic polymer. In some embodiments, the sidewall dielectric layer 26 comprises other low-k or high-k dielectric material. In some embodiments, a trench metal liner is disposed on the sidewalls of the through substrate via 21 over the sidewall dielectric layer 26. The trench metal liner acts as a metal diffusion barrier for the first conductive layer 41. In some embodiments, the trench metal liner also contains a seed layer used during subsequent electroplating processes. In one embodiment, the first conductive layer 41 is lined with a trench metal liner comprising Ta, TaN, TiW, Ti, TiN, Ru, WN, WCN, or combination thereof. The through substrate via 21 is coupled to a back side contact 51. In various embodiments, the back side contact 51 comprises copper, although in some embodiments, the back side contact 51 comprises aluminum. In some embodiments, the back side contact 51 comprises a liner for preventing diffusion of the conductive element from the back side contact 51 into the substrate. In various embodiments, the back side contact 51 is further coupled to a bottom shield (not shown).
Although illustrated in
Embodiments of the invention describing methods of fabrication of the RF shield 8 on the system on the chip will be described using
An embodiment of the invention is illustrated in
Next, a first opening 11 is formed inside the substrate 10. The first opening 11 is formed after a masking step and in one embodiment after formation of source and drain of the active devices. Forming the through substrate via 21 after forming source and drain regions is advantageous as it allows performing the high temperature steps (for example, source/drain activation anneal) before performing the metallization steps. Although not shown in some embodiments, the first opening 11 is formed along with the formation of isolation regions (e.g., shallow trench isolations). In those embodiments, the first opening 11 is filled with a dummy material and sealed till after the source and drain regions are formed. The dummy material is subsequently removed to re-form the first opening 11. Similarly, the through substrate via 21 is formed before the metallization lines are formed. This is again advantageous as the metallization does not see the extended thermal budget required to fill and anneal the through substrate via 21.
Referring again to
The first opening 11 thus produced comprises a high aspect ratio in the range from about 1:5 to about 1:20. The top of the first opening 11 comprises a width of about 2 μm to about 20 μm. The angle of the taper varies such that the bottom width is narrower than the top width, and is in the range from about 90 to about 80 degrees.
As illustrated in
A trench liner (not shown) comprising one or multiple metal liners is deposited over the sidewall dielectric layer 26. The trench liner is ideally conformal or at least continuous, and may comprise a single layer or layer combination of Ta, TaN, W, WN, WCN, WSi, Ti, TiN, Ru as examples. The trench liner is used, for example, as a barrier layer for preventing metal from diffusing into the underlying substrate 10 and sidewall dielectric layer 26. In the described embodiment, the trench liner comprises first, second, third and fourth metal liners (not shown), although in other embodiments less or more levels of metal liners may be used.
The first metal liner is formed over the sidewall dielectric layer 26. The first metal liner forms a metal diffusion barrier. The first metal liner is formed using a chemical vapor deposition process or a plasma enhanced CVD process or a combination of both, although in other embodiments other processes may be used. In one embodiment, the first metal liner comprises a Ti/TiN layer. For example, a 5-30 nm titanium layer is deposited followed by a deposition of about a 20-100 nm TiN layer.
A second metal liner is formed over the first metal liner. The second metal liner comprises a material with a low resistivity. For example, in one embodiment, the second metal line comprises tungsten. The low resistive metal liner helps to minimize potential drop and hence reduce variations during the electroplating process. The second metal liner is deposited using a chemical vapor deposition process, although in other embodiments, other processes such as plasma vapor deposition may be used. In various embodiments, the second metal liner is deposited to a thickness of about 50 nm to about 150 nm.
A third metal liner comprising a copper barrier is formed over the second liner. The third metal liner is deposited to a thickness of about 100 to about 150 nm. The third metal liner, in various embodiments, comprises a TaN layer followed by a layer of tantalum. In one embodiment, the tantalum nitride layer is deposited to a thickness of about 20-50 nm and the tantalum layer is deposited to a thickness of about 100-150 nm.
A fourth metal liner is deposited over the third metal liner. The fourth metal liner is deposited using a plasma vapor deposition process and forms a seed layer for the electroplating process in some embodiments. The fourth metal liner comprises a thickness of about 200 to about 500 nm. In various embodiments, the fourth metal liner comprises copper. The sidewall of the first opening 11 thus comprises the sidewall dielectric layer 26 and the first, second, third and fourth metal liners. In various embodiments, the fourth metal liner may be deposited conformally or at least continuously using, for example, a metal-organic CVD (MOCVD) process or a PVD process.
A first conductive layer 41 is deposited into the first opening 11. In various embodiments, the first conductive layer 41 is electroplated over the fourth metal liner. The first conductive layer 41 comprises a conductive material, such as copper or alternatively, aluminum, tungsten, silver, gold or doped polysilicon. In various embodiments, the first conductive layer 41 comprises copper.
The top surface of the substrate 10 is planarized. In various embodiments, the planarization process comprises a chemical mechanical polishing (CMP). The CMP process removes the first conductive layer 41 and the underlying trench liner and the sidewall dielectric layer 26 from over the substrate 10. After polishing through the first conductive layer 41, the CMP process removes the first, second, third and fourth metal liners. In various embodiments, the polishing process stops on the sidewall dielectric layer 26. A post CMP clean is next performed to remove any slurry residuals.
As illustrated in the flow chart of
After forming the metallization levels, the substrate 10 is thinned by grinding from the back side. Referring to the flow chart of
Referring to
A barrier liner 48 is deposited on the back side of the substrate 10 over the second insulating layer 44 and the exposed first conductive layer 41. The barrier liner is a diffusion barrier and comprises a conductive material. The barrier liner 48 may comprise a single layer of Ta, TaN, WN, WCN, WSi, Ti, TiN, Ru or combinations as examples. The barrier liner 48 is deposited using, for example, RF magnetron sputtering. The barrier liner 48 also comprises a seed layer if the subsequent processing comprises electroplating. This seed layer may be deposited continuously using for example, an RF magnetron sputtering (PVD) or a metal-organic CVD (MOCVD) process.
A first photo resist layer 47 is spun over the barrier liner 48 and patterned. In various embodiments, the first photo resist layer 47 is a thick layer of photo resist comprising a thickness of several microns. The first photo resist layer 47 is patterned using a photo lithography step. The photo lithography step is performed through a mask with patterns for redistribution lines and through substrate vias 21. The photo lithography step exposes the barrier liner 48 separated by the resist lines.
Back side contact 51 and back side redistribution lines 52 are deposited over the exposed barrier liner 48, using for example, another electroplating process. The electroplating process deposits a conductive metal over the exposed regions of the barrier liner and seedlayer 48 (
As illustrated in
An embodiment of the invention is illustrated using a partial fill of the through substrate via 21, using
The embodiment follows the prior embodiment forming the first opening 11 and forming a sidewall dielectric layer 26, as described with respect to
As illustrated in
The embodiment illustrated in this embodiment differs from the prior embodiment described in
Subsequent processing follows as in the prior embodiments and is illustrated in
After forming the metallization levels, the bond pads and passivation layers, the back surface of the wafer is thinned to expose the sidewall dielectric layer 26. The thinning process ends after exposing the first conductive layer 41 (
An embodiment of the invention comprising concentric openings forming the through substrate via 21 is described, using
As first illustrated in
A second mask stack 103 is deposited over the second opening 12. The second mask stack 103 is patterned using a photolithography process. A subsequent reactive ion etching forms the first opening 11 (
In various embodiments, the second opening 12 comprises a trench or a via.
In one embodiment the second opening 12 in the Si substrate comprises a trench which connects several or all of the first openings 11 for the through substrate conductors 21 of the RF shield 8. In one embodiment some of the second openings 12 in the form of a trench in the Si substrate may be used to electrically connect the RF component on a first part of the substrate with the semiconductor component on a second part of the substrate. In this particular embodiment the second opening 12 used for the electrical connection between the RF component and the semiconductor component are routed through openings in the RF shield 8 without making any electrical contact to the RF shield 8.
A structural embodiment of the invention is described using
As illustrated in
As illustrated in
Although illustrated as a shield against electromagnetic radiation, the structure and methods described in various embodiments can be adopted as a heat spreader for effectively removing heat from individual components. For example, individual components of the SoC 99 are surrounded with through substrate vias 21 as described above in various embodiments, such that the heat produced by the operating devices is efficiently conducted away from the active regions.
Although embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. For example, it will be readily understood by those skilled in the art that many of the features, functions, processes, and materials described herein may be varied while remaining within the scope of the present invention.
Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
Claims
1. A semiconductor chip comprising:
- a first semiconductor component disposed on a first part of a substrate;
- a second semiconductor component disposed on a second part of the substrate, the semiconductor component and the first semiconductor component sharing a common boundary;
- through substrate conductors disposed in the substrate along the boundary and forming a fence around the first semiconductor component, wherein the through substrate conductors are discontinuous along an edge of the first semiconductor component, and wherein the through substrate conductors are arranged in a staggered formation in multiple rows around the first semiconductor component; and
- a ground potential node coupled to the through substrate conductors.
2. The semiconductor chip of claim 1, wherein the first semiconductor component comprises a radio frequency component.
3. The semiconductor chip of claim 1, wherein the through substrate conductors are lined with a dielectric liner and filled with a conductive material.
4. The semiconductor chip of claim 3, wherein the conductive material comprises a metal selected from a group consisting of copper, gold, silver, aluminum, tungsten, polysilicon and combinations thereof.
5. The semiconductor chip of claim 1, wherein a longer side of the through substrate conductors is aligned along the edge of the first semiconductor component.
6. The semiconductor chip of claim 1, wherein the through substrate conductors are staggered between the multiple rows.
7. The semiconductor chip of claim 1, wherein the through substrate conductors are spaced apart by a distance of less than about 300 μm.
8. The semiconductor chip of claim 1, wherein the through substrate conductors comprise vias or trenches.
9. The semiconductor chip of claim 1, wherein a width of the through substrate conductors is larger near a top surface of the substrate than a width of the through substrate conductors on a bottom surface, the top surface comprising active devices and being opposite the bottom surface.
10. The semiconductor chip of claim 9, further comprising another through substrate conductor, wherein a width of the another through substrate conductor is smaller near the top surface of the substrate than a width of the another through substrate conductor on the bottom surface.
11. The semiconductor chip of claim 1, wherein each one of the through substrate conductors comprises a shallow cylinder near the top surface of the substrate and a deep cylinder extending through the substrate, the top surface comprising active devices, wherein the shallow and deep cylinders are concentric.
12. The semiconductor chip of claim 1, wherein each one of the through substrate conductors comprises a trench disposed adjacent the top surface of the substrate and a deep cylinder disposed within the trench, the deep cylinder extending from the top surface to an opposite bottom surface.
13. The semiconductor chip of claim 12, wherein the trench of each of the through substrate conductors is electrically connected to at least one adjacent trench of the through substrate conductors.
14. The semiconductor chip of claim 1, wherein the through substrate conductors are designed to shield the second semiconductor component from electromagnetic radiation emitted by the first semiconductor component.
15. The semiconductor chip of claim 15, further comprising additional trenches disposed in the substrate electrically coupling the first semiconductor component with the second semiconductor component through openings between the through substrate conductors, wherein the additional trenches make no connection to the through substrate conductors.
16. The semiconductor chip of claim 1, further comprising back side contacts coupled to the through substrate conductors, the back side contacts disposed on the back side of the substrate.
17. The semiconductor chip of claim 16, wherein the back side contacts are electrically coupled to another semiconductor chip.
18. The semiconductor chip of claim 17, wherein the another semiconductor chip comprises another through substrate conductor, the another through substrate conductor coupled to the through substrate conductors through the back side contacts.
19. A semiconductor chip comprising:
- first through substrate conductors disposed around a first circuit disposed on the semiconductor chip, the first through substrate conductors coupled to a ground potential node; and
- second through substrate conductors disposed around a second circuit disposed on the semiconductor chip, the second through substrate conductors are electrically floating.
20. The semiconductor chip of claim 19, wherein the first circuit comprises a radio frequency circuit, and the second circuit comprises a high performance circuit.
21. The semiconductor chip of claim 19, wherein the first through substrate conductors are designed to shield the first circuit to and/or from RF radiation and wherein the second through substrate conductors are designed to remove heat generated by the second circuit.
22. The semiconductor chip of claim 19, wherein the first and second through substrate conductors comprise at least one different dimension.
23. A semiconductor chip comprising:
- a first circuit disposed in a first region of a substrate, the first circuit being disposed on a top surface of the substrate; and
- through substrate conductors disposed in a second region of the substrate, the through substrate conductors disposed around the first circuit, the second region comprising no active devices, wherein the through substrate conductors are designed to remove heat generated by the first circuit.
24. The semiconductor chip of claim 23, wherein the first circuit comprises a high performance circuit.
25. The semiconductor chip of claim 23, wherein the through substrate conductors are electrically floating.
26. The semiconductor chip of claim 23, wherein the through substrate conductors each have a diameter that is wider adjacent the top surface than adjacent a bottom surface of the substrate, the bottom surface being opposite the top surface.
27. A method of forming a semiconductor chip, the method comprising:
- forming a through substrate opening from a front surface of a substrate, the through substrate opening disposed between a first and a second region, the first region comprising devices for RF circuitry and the second region comprising devices for other circuitry;
- filling the through substrate opening with a conductive material;
- exposing the conductive material in the through substrate opening by thinning the substrate, the back surface being opposite to the front surface; and
- electrically coupling the conductive material with a ground potential node.
28. The method of claim 27, further comprising:
- forming the active regions before forming the through substrate opening, the active regions comprising the first region and the second region; and
- forming interconnect layers after forming the through substrate opening, the interconnect layers interconnecting the active regions.
29. The method of claim 27, further comprising:
- depositing an insulating layer on the back surface;
- depositing and patterning a first photo resist layer on the insulating layer, the patterned first photo resist layer exposing a back contact of the through substrate opening;
- depositing a conductive liner over the first photo resist layer, the barrier liner contacting the back contact;
- depositing and patterning a second photo resist layer on the conductive liner, the patterned second photo resist layer forming patterns for redistribution lines; and
- forming redistribution lines by filling the patterned second photo resist layer with the conductive material.
30. The method of claim 29, further comprising:
- etching portions of the conductive liner not covered by the conductive material; and
- depositing a passivation dielectric layer between the redistribution lines.
31. The method of claim 29, wherein filling the patterned second photo resist layer with the conductive material comprises filling by electroplating the conductive material.
Type: Application
Filed: Sep 30, 2008
Publication Date: Apr 1, 2010
Patent Grant number: 8169059
Inventors: Hans-Joachim Barth (Munich), Jens Pohl (Bernhardswald), Gottfried Beer (Nittendorf), Oliver Nagy (Vienna)
Application Number: 12/242,521
International Classification: H01L 23/552 (20060101); H01L 21/44 (20060101);